OF FOSSILS. >43 



borax, produces a quadruple fait ; and it is not 

 unlikely, but that the induitry of future ages will 

 difcover combinations of five principles, and per- 

 haps of Hill more; the difpofttion and order of 

 which may be determined by the character and 

 quantity of the feveral ingredients. 



5 LXX. slnahgout Salts. 



FOSSILS of the fee on d and third clafs become 

 true falinc fubftances, by combination with any 

 fait; and inthiscomlitbnthey are baniihcd from 

 their original claifes. Salts, fuch as thcfe, are 

 called, an.ilogous ; and according to the charac- 

 ter of their bafcs, arc of two kinds, cither earthly 

 or metallic. Whatever imparts the faline na- 

 ture ought to determine the genus. 



LXXI. Other Combinations of Salts. 



ALL earths almoft as well as metals arc not 

 only taken up by acids, but feveral fulfils befides, 

 of both claflcs are cliifolvrd by -alkaline falts, 

 and fomc even by neutral .falts ; nay, it happens 

 occafionally, that t\vo double falts will unite in- 

 to one, and form a fait of four principles. From 

 fuch multiplied and various combinations pro- 

 coed, alkalis and acid* charged with earths and 

 metals; double neutral falls, or falls of more 

 principles, containing earths and metals; double 

 earthy falls' united with double metallic fairs, 



2 which 



